Abstract
Zeolite Na–X and chitosan-modified Na–X–CS were used as adsorbents for the removal of Cu(II), Fe(III), Mn(II) and Zn(II) from aqueous solutions. They were prepared based on fly ash by hydrothermal reaction using the NaOH solution under controlled conditions. Characterization of the Na–X and Na–X–CS sorbents was made using Fourier transform infrared spectroscopy with the attenuated total reflection mode, X-ray fluorescence and X-ray diffraction, nitrogen adsorption and desorption, acidity measurements and scanning electron microscopy techniques. The effects of adsorption time, the amount of sorbent and the concentration of metal ions on the removal percentage and sorption capacities were studied. The sorption percentage increased with the increasing phase contact time and zeolite amount. The adsorption mechanism was also discussed. The results revealed that Na–X–CS adsorbs Cu(II), Fe(III), Mn(II) and Zn(II) ions more effectively than zeolite Na–X and proved that modification by CS leads to an increase in the adsorption efficiency of the zeolites.
Highlights
The problem of waters and waste waters pollution with heavy metals has been known and studied by scientists around the world for a long time
The conversion of fly ashes (FAs) under the controlled conditions was performed on a pilot scale for 24 h at 353 K
X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), adsorption and desorption isotherms (ASAP) and scanning electron microscopy (SEM) indicated that CS was successfully attached to both FA and Na–X zeolite lattice
Summary
The problem of waters and waste waters pollution with heavy metals has been known and studied by scientists around the world for a long time. The effects of heavy metals on organisms are well known and focused worldwide attention, this exposure is constantly growing because of their wide use in many fields (Jarup, 2003). Adsorption is a well-known method, which is considered to be both efficient and inexpensive and often with the possibility of adsorbent reuse (Huang et al, 2016). Studies on the sorption of heavy metals are carried out on zeolites. A variety of adsorbents includes active carbons, ion exchangers and zeolites as well as a large group of low-cost sorbents such as fly ashes (FAs), biochars obtained from feedstock materials, etc
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